She is voiced by Tara Strong.
Seasons 1 and 2 of the series were highly prominent of her, but starting from Season 3 she was mostly absent due to Hasbro's interference ordering the writers to use Sari a lot less frequently.
In Seasons 1 and 2, Sari as an adolescent child was much more into exploiting her key (which absorbed the AllSpark power) and sweets (marshmallows, chocolate, candy, etc.) rather than helping out the Autobots on their task at hand. While Bumblebee and Bulkhead were personally laid-back and therefore obeyed Sari's every whim, it was becoming clear that she was being irresponsible with her key, draining it of valuable power just so she can unlock electronically-locked doors, empty out candy vending machines, and turn on music players. She was ever confident that she can handle the Decepticons as while ironically even the Autobots who were much bigger and stronger than her could only panic if Decepticons ever appeared. Despite her childish ways, the Autobots still relied on her as a moral compass on how to adapt to earth culture. Sari also got forced to correct several of what Bumblebee says or does, since Bumblebee wasn't very bright usually making more poor choices than right ones.
Later on in Season 3, it turns out that she is really a robot infused with human biology, thus a cyborg or a techno-organic. This outrages Sari and she loses faith in her father Issac as well as Optimus Prime (who was only trying to get Sari to love her father again). During a confrontation with Headmaster, she then came to accept her biological identity due to her powers being capable of helping out Autobots against threats such as the Headmaster and a rocky turtle-like alien. She also loses the key, having absorbed all the power inside it to upgrade herself, earning an exo-suit, a hammer, and even advanced through age. She no longer is the once immature girl back earlier in the series and is now thoroughly much more mature. she and bumblebee might be more than friends and cause of it they are in love.
Season 4 was supposed to have focused on Sari's origins more, but the series has been cancelled.
As a human, Sari is dark-skinned with red hair tied into long pigtails and bangs parted from the left with two orange and white hair clips holding them in place and maroon eyes. She also wears a long-sleeved dress in orange with a white stripe that goes up to her neck and stops above the knees, white socks, and orange boots with white wedges.
When she upgraded herself in TransWarped, Sari gained a more mature, robotic body. Her dress and socks are longer and have the attributes of any Cybertronian, including her helm with winglike attachments due to the fact that her pigtails became shorter, and her eyes are blue like the Autobots'. In between transformations, the sleeves now act like gloves on her hands, and her shoes are much bigger than before. Her dress also comes with a white gorget with a light blue gem.
Sari is a sweet and smart girl, but rather immature and rarely obedient. She can sometimes behave in excessive proportions, such as when she tries to sabotage the Autobot ship to prevent them from leaving. Nevertheless, she has a good heart and a strong sense of humor. Despite her age, Sari is often very protective of her father and the Autobots, who are her only true friends and family. When her father is kidnapped in La Garde d'Elite, she spends large sums of money on society trying to find him. She is constantly looking to help the Autobots in the battles, which is (to his exasperation) almost always refused by the latter. She can however assist them in the fight since season 3.
Power and Skills
Originally, Sari did not initially have real powers, but his Key had some of the powers of the Matrix. This essentially allowed him to control / hack non-intelligent machines, and instantly repair all machines in general, including Autobots. She was even on one occasion able to save Optimus from death. The Key also had the ability to bring machines to life, as we saw when it allowed Dinobots to develop sparks and move from simple robots to live, conscious transformers. Occasionally, the Key also detected the danger and fragments of the Matrix, and Sari used it to open a rift in the Shield of the Elite Guard Ship.
In addition to his key, Sari is intelligent and resourceful, able to cope with various situations. She also received from Prowl a training in Martial Arts, certainly not useful against really powerful opponents, but still interesting to diversion. At some point in history, she was able to surpass the Constructicons in intelligence and make them run away.
When her techno-organic nature is revealed in season 3, she discovers a power when Powel and Henri Masterson, dismissed, insult her with her father: under the effect of anger, she performs a kind of "semi-transformation" "(His hands unfold to reveal robotic parts) and projects them a sort of shockwave. It reuses this attack two or three times thereafter. His shots thus executed have only a minor power, but still of size.
When it improves with the Key, it gets a more robotic appearance, as well as a whole arsenal of energy weapons, including among others "rollers", a hammer and blades on the forearms. This new shape also greatly increases its strength, speed and probably its resistance, making it able to use Prowl training with real efficiency. It can still generate shock waves, although these are more powerful than before, only one of which is enough to hurt Soundwave. It has been seen in Human Error that Sari can alternate between his robotic aspect and his aspect of human teenager, or put himself between them, in the same way that the Autobots are transformed. In the same episode, we learn that she is immune to Soundwave's hypnotic music because of its techno-organic nature.
It is revealed in episode 39 that the key seems to have improved his brain / processors, making it able to repair Cybertronian technologies without his Key, as well as some technopatic gift allowing him to talk to machines for analyze what to change.
In a comic book of season 4, on discovering the origins of Sari who is the avatar of the allspark could possibly control and invoke it. She has a telepathic connection with and can communicate with others. Also, transmit energy to transformers by touching them or invoking the energetic vertiation of their key.